The Norwegian Safety Authority (NSA) has issued state-owned Statoil with an official safety order following an oil leak.
The NSA carried out a complete investigation into the January 26 incident which resulted in the four-day shutdown of Statoil’s Statfjord C platform. A total 42 cubic metres of oil – more than 200 barrels – were estimated to have escaped in 37 minutes, at a rate of 20.8 kg per second. The NSA found possible consequences of the spill in the ‘event of ignition’ to include spray fire and the combustion of oil drops.
It also said the probability of a similar leak was ‘high’ in the wake of the spill.
The NSA uncovered six nonconformities in its investigation, including the original design solution for the drainage system, the modified design solution of the drainage system, consequence classification of the open drainage system, preparations for maintenance, management of simultaneous activities and the qualification and follow-up of contractor expertise.
It also made four improvement points covering Statoil’s own investigation into the leak, its potential consequences and ‘a failure to address the underlying causes of the incident adequately’.
Statoil now has until October 1 to comply with the order and address the various points made by the NSA.
The Statfjord field is one of the oldest Norwegian oil fields, originally discovered in 1974, with the Statfjord C platform beginning production in June 1985.
It straddles the UK and Norwegian continental shelves, with production of around 23,000 barrels of oil per day.
Less than two years ago a leak of toxic hydrogen sulphide gas on Statfjord C saw the platform shut down, while in 2007 more than 21,000 barrels worth of oil was spilled from a tanker during loading from the neighbouring Statfjord A.
As part of its investigation the NSA found: “The hydrocarbon leak occurred while stabilised oil was being transferred from Statfjord A to Statfjord C.
“At the same time, preparations were being made for maintenance work on a loading pump in the shaft. An isolation valve for the pump sprang a leak, causing the pump house to fill with oil. This oil drained to the sump tank at the base of the shaft via an open drain valve. When the level in the sump tank reached 70 per cent, the pump for transferring liquid from the sump tank to the oily water tank beneath the cellar deck started up. The valve controlling the level in the oily water tank failed to open, and oil escaped via fire seals on the cellar deck.”